Grand canonical Monte Carlo simulation of adsorption of nitrogen and oxygen in realistic nanoporous carbon models

Adsorption of nitrogen and oxygen in nanoporous carbons (NPC) is simulated using grand canonical Monte Carlo simulations, where the Steele potential (developed for gas interactions with graphite) is used to represent gas–carbon interactions. NPC models used for the adsorption simulations are developed using an isothermal‐isobaric (constant NpT) ensemble Monte Carlo algorithm whereby an initial polymer chain is evolved through a series of atomic displacement and bond rearrangement steps into the final carbon structure. These constant NpT carbon models are representative of real NPCs in terms of local structure and chemical composition. Predictions of nitrogen and oxygen sorption from our model NPCs show good agreement with experimental data. The isosteric heats of adsorption of both adsorbates lie within the range of experimental values for NPCs. Furthermore, the adsorption isotherms of the two gases showsemi‐quantitative match with experimental adsorption isotherms. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

The Reprimo-Like Gene Is an Epigenetic-Mediated Tumor Suppressor and a Candidate Biomarker for the Non-Invasive Detection of Gastric Cancer

Reprimo-like (RPRML) is an uncharacterized member of the Reprimo gene family. Here, we evaluated the role of RPRML and whether its regulation by DNA methylation is a potential non-invasive biomarker of gastric cancer. RPRML expression was evaluated by immunohistochemistry in 90 patients with gastric cancer and associated with clinicopathologic characteristics and outcomes. The role of RPRML in cancer biology was investigated in vitro, through RPRML ectopic overexpression. Functional experiments included colony formation, soft agar, MTS, and Ki67 immunofluorescence assays. DNA methylation-mediated silencing was evaluated by the 5-azacytidine assay and direct bisulfite sequencing. Non-invasive detection of circulating methylated RPRML DNA was assessed in 25 gastric cancer cases and 25 age- and sex-balanced cancer-free controls by the MethyLight assay. Downregulation of RPRML protein expression was associated with poor overall survival in advanced gastric cancer. RPRML overexpression significantly inhibited clonogenic capacity, anchorage-independent growth, and proliferation in vitro. Circulating methylated RPRML DNA distinguished patients with gastric cancer from controls with an area under the curve of 0.726. The in vitro overexpression results and the poor patient survival associated with lower RPRML levels suggest that RPRML plays a tumor-suppressive role in the stomach. Circulating methylated RPRML DNA may serve as a biomarker for the non-invasive detection of gastric cancer.     

Fundamentals of the refractory wear in an industrial anode furnace used in the copper-making process

This paper presents a combination of different useful techniques to identify the fundamentals of the infiltration and chemical degradation of the refractory used in the lining of an anode furnace for fire refining of blister copper. In practice, this work was carried out at the Atlantic Copper Smelter (Huelva; Spain) by a post-mortem study of the refractory used in a one-year campaign, and thermochemical calculations using the FactSage^® database. The combination of both techniques created enhanced value thanks to their synergy.The infiltrations and the formation of new phases in the reaction layer were identified using microstructural analyses. The nature of these infiltrations were identified; all the refractory brick samples had been substantially infiltrated by copper and slag elements (mainly copper and iron oxides). The new phases formed were the result of the complex chemical interaction between the slag and the constituent of the refractory. Additionally, copper was incorporated to the spinel.In order to propose a model to represent this complex process, thermochemical calculations were carried out to define a baseline to explain the microstructures obtained as a consequence of the interactions between the bath and the refractory.     

A dynamic model of a liquid helium transfer line at the Canadian Light Source

This paper describes the creation and validation of a computer model of a liquid helium transfer line located at the Canadian Light Source (CLS) in Saskatoon, Canada. This line transfers liquid helium to a cryostat, which contains a superconducting radio frequency (RF) cavity, and requires precise pressure and level modulation to ensure proper RF control. A detailed mathematical model of the transfer line is created based on mass, momentum, and energy continuity along with pressure–volume–temperature relations. The model is discretized and solved, and model results are compared with experimental data taken from the actual cryostat at the CLS to validate of the simulation. The validated model is found to reasonably predict flow rates through the transfer line at the CLS from a process perspective.     

Stability of ethyl esters from soybean oil exposed to high temperatures in supercritical ethanol

It is well known that during the supercritical alcoholysis of vegetable oils the main transesterification reaction occurs simultaneously to several decomposition phenomena, In order to separately study the effect of such phenomena, pure ethyl esters from soybean oil (SBOEE) were mixed with ethanol at a molar ratio 40:3 (ethanol:SBOEE) and exposed for different periods to supercritical conditions in a continuous system, at 20 MPa and different temperatures from 250 to 375 °C. It was experimentally observed that the ester content of the processed samples were lower than that corresponding to the original SBOEE, indicating the occurrence of decomposition processes, which were more important as the temperature increased and the flow rate diminished. The content of polyunsaturated esters of the treated SBOEE was lower than that of the starting mixture, showing that the decomposition rate was highly dependent on the nature and instauration degree of the alkyl chain.     

Table-based PWM for all-digital RF transmitters

In this paper, a novel pulse-width modulator (PWM) for an all-digital PWM transmitter based on switching amplification is presented. In this approach, each symbol is represented by a sequence of pre-computed PWM pulse widths stored in a table that results in reduced error vector magnitude (EVM). A high-resolution pulse former is then used to build the bipolar radio frequency (RF) signal. Simulations and comparisons to other approaches reported in the literature under different oversampling ratios and finite time resolutions are presented. The impact of nonlinearities in the variable duty-cycle generator is also analyzed to demonstrate the robustness of the proposed technique.     

Design space description through adaptive sampling and symbolic computation

Design space definition is one of the key parts in pharmaceutical research and development. In this article, we propose a novel solution strategy to explicitly describe the design space without recourse decisions. First, to smooth the boundary, the Kreisselmeier–Steinhauser (KS) function is applied to aggregate all inequality constraints. Next, for creating a surrogate polynomial model of the KS function, we focus on finding sampling points on the boundary of KS space. After performing Latin hypercube sampling (LHS), two methods are presented to efficiently expand the boundary points, that is, line projection to the boundary through any two feasible LHS points and perturbation around the adaptive sampling points. Finally, a symbolic computation method, cylindrical algebraic decomposition, is applied to transform the surrogate model into a series of explicit and triangular subsystems, which can be converted to describe the KS space. Two case studies show the efficiency of the proposed algorithm.     

Remittances and educational outcomes: a regional investigation for Moldova

This paper looks at the relationship between remittances and higher education in Moldovan regions. The objective is to test whether remittances are associated with an increase in the likelihood of attending higher education institutions by taking into account a possible disruptive effect of migration and looking for regional differences in this relationship. Findings show that, on average, remittances are associated with a 5.4 percentage point increase in the likelihood that young individuals will pursue higher education. Nonetheless, this result is widely heterogeneous across regions.